Most biologic experiments, of necessity, have been heretofore conducted with gravity as a constant, and thus, the relationships between gravity and fundamental cellular mechanisms are unknown. Use of the space microgravity environment, graded levels of gravity by centrifugation in space, and the unit gravity control situation on earth can provide a unique method for evaluating the interrelation of all structures and functions.
Microgravity experiments require a means to add stimulants (e.g., hormones) to cells at various times, followed by a means to either: (a) observe and record the cellular response or (b) add chemicals to preserve cellular structure and features (fixation) for later detailed analysis.
Common methods of fluid addition (e.g., syringes, pumps, moving valves, etc.), require significant power for operation, are often large and fragile and sometimes require secondary mixing to assure dispersion. These features severely reduce the number of duplicate units that can be used in a single space mission. The prior art contains a number of examples of such mixing systems. In Carter et al. U.S. Pat. No. 4,909,933, a multi aperture mixing system is described which employs a rotatable valve that enables the contents of either two or three interconnected chambers to be intermixed in a low gravity environment. In Hise et al. U.S. Pat. No. 3,769,176, a dialysis system employs gas pressurized pump chambers to provide remote feeds for reactants.
The prior art contains a variety of systems for moving a fluid from one chamber to another chamber for the purpose of carrying out a reaction. In Tschopp and Suiter U.S. Pat. No(s). 4,680,266 and 4,783,413, respectively, osmotic pumps are employed wherein the migration of one fluid through a permeable membrane into the interior of the pump chamber, causes an increase in pressure therein which in turn forces out a reactant fluid. In Lee U.S. Pat. No. 4,208,483, a cylindrical bottle filled with a culture medium has a rotatable shaft therein with treated disks that are mounted at an angle to the shaft and are rotatable therewith. The reactant fluid is pumped along the length of the chamber by the rotation action of both the shaft and the disks. In Tanner et al. U.S. Pat. No. 3,134,650, air-pulse operated liquid mixing systems are disclosed. Many patents show the use of reciprocal pump-driven reactant mixing systems and these include Pontigny U.S. Pat. No. 3,496,970, Phelan U.S. Pat. No. 3,800,984, and Slaven U.S. Pat. No(s). 4,350,429 and 4,366,839.
The prior art also discloses a number of reaction chamber structures for carrying out various biochemical reactions. Such systems are shown in Paul U.S. Pat. No. 2,975,553, Miltonburger et al. U.S. Pat. No. 4,649,114, Robertson et al. U.S. Pat. No. 4,873,057, and Holmquist et al. U.S. Pat. No. 4,908,187. Further details of such systems, such as fluid flow control devices, flow control capillary systems, reaction chamber assemblies etc. are shown in Gilmont U.S. Pat. No. 2,988,321, Brown U.S. Pat. No. 4,676,274, Karlberg et al. U.S. Pat. No. 4,399,102, McKnight U.S. Pat. No. 4,563,336, and Parham U.S. Pat. No. 4,566,480.
A common feature of substantially all of the system and subcomponent prior art references described above is their requirement for powered pumping systems, their requirement for relatively precisely machined parts and, in many instances, a significant level of complexity.
Accordingly, it is an object of this invention to provide a system for mixing of reactant fluids which is both simple of construction and inexpensive.
It is another object of this invention to provide a system for remote mixing of fluids wherein power requirements are minimized.
A further object of this invention is to provide a system for remote mixing of fluids in a microgravity environment.